Stability of gene expression in human T cells in different gravity environments is clustered in chromosomal region 11p15.4

Abstract

In the last decades, a plethora of in vitro studies with living human cells contributed a vast amount of knowledge about cellular and molecular effects of microgravity. Previous studies focused mostly on the identification of gravity-responsive genes, whereas a multi-platform analysis at an integrative level, which specifically evaluates the extent and robustness of transcriptional response to an altered gravity environment was not performed so far. Therefore, we investigated the stability of gene expression response in non-activated human Jurkat T lymphocytic cells in different gravity environments through the combination of parabolic flights with a suborbital ballistic rocket and 2D clinostat and centrifuge experiments, using strict controls for excluding all possible other factors of influence. We revealed an overall high stability of gene expression in microgravity and identified olfactory gene expression in the chromosomal region 11p15.4 as particularly robust to altered gravity. We identified that classical reference genes ABCA5, GAPDH, HPRT1, PLA2G4A, and RPL13A were stably expressed in all tested gravity conditions and platforms, while ABCA5 and GAPDH were also known to be stably expressed in U937 cells in all gravity conditions. In summary, 10–20% of all transcripts remained totally unchanged in any gravitational environment tested (between 10−4 and 9 g), 20–40% remained unchanged in microgravity (between 10−4 and 10−2 g) and 97–99% were not significantly altered in microgravity if strict exclusion criteria were applied. Therefore, we suppose a high stability of gene expression in microgravity. Comparison with other stressors suggests that microgravity alters gene expression homeostasis not stronger than other environmental factors.

Rapid Cellular Perception of Gravitational Forces in Human Jurkat T Cells and Transduction into Gene Expression Regulation

“…The TEXUS-51 mission procedures have been previously described [13,14,55,56]. Briefly, three syringes were assembled into one unit.…”

“…Human Jurkat T cell culture was performed as previously described [13,14,55,56] in the ESRANGE Space Center laboratory facilities. Briefly, sterile plastic syringes were filled with 0.5 mL Jurkat cells (25 million cells).…”

“…The human organism reacts and partially adapts to altered gravity [2,3] in a time frame of a few hours up to several weeks [4]. The cellular response to microgravity, such as functional alterations [5,6], nucleus size, and shape [7][8][9], and RNA transcription [10,11] mostly occurs within seconds, sometimes months [12][13][14][15]. The question about the mechanism by which gravitational force is transmitted into a biological process was raised decades ago [16,17], but it was rarely addressed in experimental approaches.…”

“…At the cellular level, changes of the gravitational force affect morphology, proliferation, differentiation, signal transduction, and gene expression [45] and have been detected within seconds in isolated cells of the immune system [10,12,13,46,47]. We recently investigated the dynamics of gene expression response to different gravitational environments in human Jurkat T lymphocytes in combination of parabolic flights with a suborbital ballistic rocket experiment and with control experiments for excluding all possible other factors of influence [13,14]. In these experiments, we detected a significantly high number of differentially regulated transcripts after 20 s of microgravity exposure [13], and gene clusters which are stable in different gravity environments [14].…”

“…We recently investigated the dynamics of gene expression response to different gravitational environments in human Jurkat T lymphocytes in combination of parabolic flights with a suborbital ballistic rocket experiment and with control experiments for excluding all possible other factors of influence [13,14]. In these experiments, we detected a significantly high number of differentially regulated transcripts after 20 s of microgravity exposure [13], and gene clusters which are stable in different gravity environments [14]. According a recent comparison, the biological responses of cells in suspension in a 2D clinostat is similar to those in flight-induced microgravity [20].…”